Random Thoughts from the High Desert
Written by Sig Silber
Recently the U.S. Government issued an updated version of their National Climate Assessment. It can be found here.
There is a chapter on agriculture which can be found here. It draws the following conclusion:
"Climate change impacts on agriculture will have consequences for food security both in the U.S. and globally".
Unfortunately this report has many deficiencies.
Two of the most significant deficiencies are:
A. The authors are (purposely?) unclear as to whether they are talking about the impact of anthropogenic climate change or what the IPCC calls internal variability: that is natural cycles most of which are controlled by oceans.
B. The draft of the agriculture chapter of this report is dated January 2013 meaning it was written in 2012 and thus it is not based on the IPCC (Intergovernmental Panel on Climate Change) Fifth Assessment...i.e. the U.S. Government Report was out of date on the day the IPCC assessment was issued. The U.S. government report was based on out-of-date IPCC documents.
Note: This is not unusual as it takes the U.S. Government a long time to produce a report and in New Mexico, the Bureau of Reclamation (BOR) Report on the Upper Rio Grande also suffered from among other things relying on outdated information. They ignored internal variability when making their temperature forecast which can be traced to not having read the IPCC Fifth Assessment where this was discussed in great detail.
Not to dismiss the importance of anthropogenic climate change (due to GHG emissions and land-use modification) but the ocean cycles have played a large role in determining growing conditions in the U.S. for many thousands of years. Two sources of useful information in this regard can be found here and here. They both say about the same thing but the second reference is more recent. There have been many papers written on this subject since then but they are very technical so I have not referenced them in this discussion.
Here is the assessment the authors of the studies linked came up with in 2004:
The red areas are unusually dry, the blue areas are unusually wet.
- AMO refers to the condition of the North Atlantic with "+" being the positive or warm phase and "-" being the negative or cold phase.
- PDO refers to the condition of the Northern Pacific with its phases similarly noted.
I have not checked to see if the 2008 version of these graphics are different but if it is it would be a very slight difference since if recalculated, the number of additional years of data would have been small. These four graphics refer to drought frequency but a similar analysis could have been done for temperature.
Since 1998, we have been in the -PDO/+AMO condition which means a high probability of drought in the Southwest. That does not mean that Anthropogenic Climate Change has not made this drought more intense but it strongly suggests that the Southwest would be experiencing drought even if greenhouse gases (GHG) were not increasing. In addition to these multidecadal cycles there is also the shorter ENSO (El Nino - Southern Oscillation) cycle with its two phases La Nina and El Nino. In addition there are other ocean cycles also that impact climate in the U.S.
So this raises serious questions about the objectivity of the group within the U.S. Government that prepares these Climate Assessments. It is preposterous to conclude that they do not know about Ocean Cycles. So what then is the conclusion that one might draw?
It is not a pretty one. In fact it stinks of politics.
By the way: There is an interesting quote 7.2.2 from the WG2 final accepted IPCC Draft Report on the "Impacts, Adaptation and Vulnerability" resulting from Climate Change which can be found here.
"Food production is an important aspect of food security (7.1), and the evidence that climate change has affected food production implies some effect on food security. Yet quantifying this effect is an extremely difficult task, requiring assumptions about the many non-climate factors that interact with climate to determine food security. There is thus limited direct evidence that unambiguously links climate change to impacts on food security."
So the two reports appear to be somewhat (not totally) in conflict.
Again it looks like some in the U.S. Government have their own agenda. I prefer science to politics. Adaptability allows for improved response to climate and weather variation independent of the cause. Studies show that the results with significant adaptability can be as much as 50% better than modeled results that assume no adaptability. But of course society does adapt to change. So model results that assume no adaptability are only useful in terms of demonstrating the need for and value of adaptability.
Just as in all branches of economics, change creates challenges and opportunities. If you ignore the opportunities, the likely outcomes are biased towards the negative so hopefully responses to the natural and anthropogenic variations in climate will be focused on how to maximize the opportunities while minimizing the downside risks.